INCREASED SEEDLING ESTABLISHMENT OF IMPATIENS WALLERANA IN RESPONSE TO LOW TEMPERATURE OR POLYETHYLENE GLYCOL SEED TREATMENTS
Seeds of Impatiens wallerana ’Elfin Scarlet’ were pre-treated with low temperature (8 °C) imbibition and hypertonic osmotic solutions of polyethylene glycol (PEG) 6000 in an attempt to improve seedling establishment under greenhouse conditions. Seeds held at 8 °C for 7 or 14 days germinated faster at 25 °C than non-treated seeds; seedling development was more rapid and there was a significant improvement in seedling establishment. Application of a soil cover improved seedling establishment in both control and pre-treated seeds. PEG pre-treated seeds germinated within 24 h of being released from osmotic control. The optimum pre-treatment was determined to be PEG −7.5 bars for 10 days, which resulted in 80% germination within 24 h, more advanced seedling development after 5 days, 92% seedling establishment and earlier flowering. Although PEG pre-treatments were superior to the low temperature pre-treatments, they are not readily applicable on a large scale. However, low temperature seed pre-treatment can be easily utilized to improve seedling establishment in commercial production.